Synthesis, Magnetic, Spectroscopic and Electrochemical Studies of Mixed Pyrimidine-2-thiolate/triphenylphosphine Rhenium(V) and Rhenium (III) Complexes.

Equimolar amounts of trans-[ReOX2(OEt)(PPh3)2] (XCl, Br, I) precursors and potentially bidentate N,S-donor pyrimidine-2(1H)-thione (pymSH) react in refluxing acetone to give mononuclear octahedral paramagnetic trans-[ReIIIX2(pymS)(PPh3)2](XCl, Br, I) species. Starting from a metal–ligand molar ratio of 1:3, in the presence of N(C2H5)3 as deprotonating agent inrefluxing ethanol, the same reaction proceeds stepwise, affording octahedral [ReO(pymS)3] or [ReO(pymS)3] and pentagonalbipyramidal[Re(pymS)3PPh3] complexes as a function of the reaction time. The compounds were characterized by elementalanalysis, magnetic susceptibility, UV–Vis–NIR, IR and 1H NMR spectroscopy and by cyclovoltammetric measurements.Reaction pathways and physico-chemical properties of the complexes are discussed

Characterization and Functional Complementation of a Nonlethal Deletion in the Chromosome of a β-Glycosidase Mutant of Sulfolobus solfataricus

LacS(−) mutants of Sulfolobus solfataricus defective in β-glycosidase activity were isolated in order to explore genomic instability and exploit novel strategies for transformation and complementation. One of the mutants showed a stable phenotype with no reversion; analysis of its chromosome revealed the total absence of the β-glycosidase gene (lacS). Fine mapping performed in comparison to the genomic sequence of S. solfataricus P2 indicated an extended deletion of ∼13 kb. The sequence analysis also revealed that this chromosomal rearrangement was a nonconservative transposition event driven by the mobile insertion sequence element ISC1058. In order to complement the LacS(−) phenotype, an expression vector was constructed by inserting the lacS coding sequence with its 5′ and 3′ flanking regions into the pEXSs plasmid. Since no transformant could be recovered by selection on lactose as the sole nutrient, another plasmid construct containing a larger genomic fragment was tested for complementation; this region also comprised the lacTr (lactose transporter) gene encoding a putative membrane protein homologous to the major facilitator superfamily. Cells transformed with both genes were able to form colonies on lactose plates and to be stained with the β-glycosidase chromogenic substrate X-Gal (5-bromo-4-chloro-3-indoyl-β-d-galactopyranoside)

Synthesis, crystal and molecular structure, spectroscopic and electrochemical studies of trichloro-oxo(4,6-dimethypyrimidine-2(1H)-thione)(triphenylphosphine oxide) rhenium(V) complex.

Reaction of 4,6-dimethylpyrimidine-2(1H)-thione (Me2pymSH) with mer-[ReOCl3(Me2S)(OPPh3)] synthon in 1:1 molar ratio inrefluxing acetone, results in the replacement of the Me2S ligand to form the mer-[ReOCl3(Me2pymSH)(OPPh3)] species. X-raydiffraction shows that the structure of the title compound consists of monomeric units with a distorted octahedral coordinationaround the rhenium(V) centre which includes the axial ReO and ReOPPh3 bonds, and in which three Cl− ions and aS-monodentate neutral Me2pymSH ligand act as equatorial ligands. The compound was also characterised using electrochemicalmeasurements and UV–Vis–NIR and IR spectroscopy

Molecular biology of fuselloviruses and their satellites

Fuselloviruses, also known as Sulfolobus Spindle-shaped viruses (SSVs), are "lemon"- or "spindle"-shaped double-stranded DNA viruses. Among them, SSV1, SSV2 and the satellite viruses pSSVx and pSSVi have been investigated at the structural, genetic, transcriptomic, proteomic and biochemical levels, thus becoming models for dissecting DNA replication/gene expression in Archaea. Important progress has been made including elucidation of temporal genome expression during virus infection and induction of replication, SSV1 lysogeny maintenance as well as differentially expression of pSSVx replicase. Future researches focusing on these model systems would yield insightful knowledge of life cycle and DNA replication of fuselloviruses

An Autonomously Replicating Transforming Vector for Sulfolobus solfataricus

A plasmid able to transform and to be stably maintained both in Sulfolobus solfataricus and in Escherichia coli was constructed by insertion into an E. coli plasmid of the autonomously replicating sequence of the virus particle SSV1 and a suitable mutant of the hph (hygromycin phosphotransferase) gene as the transformation marker. The vector suffered no rearrangement and/or chromosome integration, and its copy number in Sulfolobus was increased by exposure of the cells to mitomycin C

Coordination Chemistry of Thio- and Oxo-Pyrimidine Derivatives

Coordinative behaviour of thio- and oxo-pyrimidine towards several metal ions are reviewed emphasizing the role of the tautomeric equilibrium. Typical bonding modes, including simple donation, chelation or bridging are discussed on the basis of spectroscopic and structural results